Quirks & Quarks

Darn gut bacteria might be thwarting your weight loss efforts

The patients who didn't lose weight had bacteria that was more efficient in extracting energy from food.
A new study on patients in a weight loss program found that those who did not lose weight had different gut bacteria than those who did. (AFP/Getty Images)
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Weight loss microbes

A whopping 54 per cent of Canadians over the age of 18 self-reported as overweight or obese in 2014, according to Statistics Canada. And many feel like it's an uphill battle no matter what they do.  

Take Ian Patton, Public Engagement Manager at Obesity Canada, for example. He was 360 pounds at his heaviest, and has been struggling with weight issues since he was a child.

What we realized was that some of the patients who did not lose weight, they had different bacteria than the others. And those bacteria had the capacity to extract more energy from the diet compared to other bacteria.- Dr. Vandana  Nehra  

"I've tried a lot of different diets and exercises, food restrictions. I've tried them all," said Patton. "I've spent many hours in the gym working out, I know all about food and exercise, and none of it has seemed to work fully."

Now, Dr. Vandana Nehra, a gastroenterologist and Associate Professor of Medicine at Mayo Clinic's College of Medicine, and her team have figured out why some people might have a harder time slimming down than others. By examining the gut bacteria of obese patients in a weight loss program, Nehra thinks certain microbes could be wrecking all their hard work.

The numbers were all over the board

To study the link between gut bacteria and weight loss, Nehra collected stool samples from 26 patients enrolled in the Mayo Clinic Obesity Treatment Research Program in 2013. All of them went through the same high fibre, low-calorie diet and exercise regimen.

At the end of the six-month study, 72 per cent of the patients lost weight, while 27 per cent saw no change. Of the 72 per cent that did lose weight, the numbers were all over the board from five to 10 pounds lost to more than 20 pounds.   

Some gut bacteria can break down complex food particles that our body normally can't better than others. But when it goes unused, all that extra energy gets stored as fat (Pacific Northwest National Laboratory, cc-by-nc-nd-2.0)

"What we realized was that some of the patients who did not lose weight, they had different bacteria than the others," said Nehra. "And those bacteria had the capacity to extract more energy from the diet compared to other bacteria."

Nehra explained that some bacteria can break down complex food particles that our body normally can't better than others. This may sound like a good thing since it's providing us with more energy. But when it goes unused, all that extra energy gets stored as fat.

For example, the bacteria phascolarctobacterium in the study was associated with weight loss success, while dialister was associated with failure to lose weight.

Individualized treatment for obesity

"Our aim was to see if we can use this as a predictor to see who would respond to the lifestyle modification treatment rather than investing a whole year and not having any response to it," said Nehra.

The research team's ultimate goal is to use the information about a patient's gut bacteria to recommend the appropriate weight loss program.

"In this day of individualized medicine, we want to see how we can tailor the treatment to everybody's individual needs rather than having one treatment protocol for everybody."

Can we change our gut bacteria makeup?

It's important to note that gut bacteria is just one of many factors involved in obesity, reminds Nehra. Exercise, nutrition and lifestyle will always be important, and perhaps the most essential advice is still to eat a nutritious and fibre-rich diet.

Also, while there is a growing body of research pointing to a link between the gut microbiome and obesity, this is a preliminary finding in a small study, acknowledged Nehra. More research is needed to confirm the effects of gut bacteria in weight loss. 

In the future, she would like to look at how to change one's gut environment so that it's more conducive to weight loss as well.

There's a huge interest in using probiotics and prebiotics to add beneficial bacteria to the gut and to treat all kinds of medical conditions including weight loss, said Nehra, but she thinks the first step would be to use dietary manipulation to change the internal environment.